Automatic machinist



HJM

All@ 2, 1960 C. H. KILLIAN 2,947,928

AUTOMATIC MACHINIST Aug. 2, 1960 AUTOMATIC MACHINIST Original Filed May18, 1945 'G I sPEcTzR Aug' 2 1960 c. H. KsLLlAN 2,947,928

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AUTOMATIC MACHINIST Original Filed May 18, 1943 l0 Sheets-Sheet 6 k2.Q'. HIHIII FIG. I6

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PUNCHED TAPE FEEDS SENSE!) TAPE FEEDs NORMA.

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AUTOMATIC MACHINIST Original Filed May 18. 1945 10 Sheets-Sheet 10 Y LTEFIG.23

United States Patent O AUTOMATIC MACHINIST Cletus H. Killian, Brooklyn,N.Y., assignor o f one-fourth to R. K. Le Blond Machine Tool Co.,Cincmnatl, Ohio, a corporation of Delaware Substituted for abandonedapplication Ser. No. 487,443, May 18, 1943. This application Oct. 7,1952, Ser. No. 313,536

9 Claims. (Cl. S18-23) This application is a substitute for my abandonedapplication, Serial Number 487,443, led May 18, 1943.

My invention relates to improvements in the process and/or methods ofautomatically controlling various instrumentalities such as variousmachine tools, as for eX- ample lathes, milling machines, saws, planets,Shapers, profilers, etc., or of other devices having optionallyadjustable means under control of an operator as for example chemicalreaction devices, various paper machines (Yankee, vFourdriniers, etc.),molding machines of various sorts, furnaces, textile machines or thelike. This invention is an improvement in part, and a continuation inpart of my prior applications for patent, Serial Number 248,062, filedAugust 23, 1951, Serial Number 20,018, filed May 6, 1935; Serial Number481,940, led April 5, 1943; and Serial Number 74,327, filed April 14,1936, now all abandoned, for this invention in common with theinventions in cited applications for patent comprises both perforatedtape sensing mechanisms and tape punching mechanisms as well as otherdevices to be controlled thereby.

The fundamental principles of this invention have been fully disclosedin certain of the inventors co-pending applications. The functioning ofa machine tool in accordance with av predetermined schedule has been setforth in the application of C. H. Killian, Serial Number 74,327, filedApril 14, 1936, for Method and Process for Die Sinking, now abandoned.The description of the component parts of the control mechanism has beenfully set out in the application of C. H. Killian, Serial Number 20,018,filed May 6, 1935, for Kalkulex Systems, now abandoned. A furtherdevelopment of the latter appears in the application of C. H. Killian,Serial Number 481,940, filed April 5, 1943, for Kalkulex Systems, nowabandoned. The inventions disclosed herein are improvements, in part,and continuations, in part, of the cited applications for patents.

The mechanism to be described has been constructed and has beeninexperimental use for some time in cutting irregular contours byautomatically controlling the work feeding elements of a profilingmachine. This experimental work included the construction of arbitraryirregular contours corresponding to shapes required for small arms,contour templates required for shaping and gauging airplane parts suchas propellers, etc. Experience has clearly demonstrated thatsurprisingly exact duplications can be readily obtained, that aperforated tape corresponring to an irregular template or contour can beconstructed ab initio, or duplicated in a time that is negligible incomparison with the usual procedure. One spectacular result includes theshaping or fashioning of complex parts at a single set up on one machinetool by the use of an appropriate perforated tape which corresponds tothe part to be fashioned.

This invention relates to improvements in automatic controls formachinery in general, but, more specically, it is shown and described inconnection with a machine tool. The broad aspects of this invention areadaptable ice to any machine having optionally adjustable controls.Thus, the usual lathe is provided with the so-called lead screw formoving the carriage along the bed; the lathe carriage is also providedwith a feed screw for adjusting the tool bit towards, or away from, thelathe centers. Again, most milling machines are provided with feeds fortransversing the table, for elevating the table, for cross feeding thetable, etc. It is Well known that such machines sometimes have rack andpinion feeds rather than screw feeds; nevertheless, the mechanisms ofthe present invention are applicable thereto. It is also well known thatother machines have such adjustable elementsas for example, someprinting presses, some reaction vessels in the process industries, somegauging machines, etc. It is to be understood that the mechanisms fullydisclosed and described herein can often be applied to such devices asoccasion may arise.

One object of the present invention is to convert a relatively simplemanually controlled machine into a more or less fully automaticmachine-as for example, a hand controlled milling machine may beconverted into a fully automatic milling machine; a hand controlledlathe may be converted into a more or less completely automatic lathe; ahand operated profiler may be converted into an automatic proler; amanually controlled reaction vessel (e.g., tire vulcanizer, digester,etc.) may be converted into a fully automatic device; etc.

Another object of this invention is to cause a suitable machine to passthrough a given number of repetitive cycles under control of a master,which is usually in the form of a perforated tape.

Another object of this invention is to automatically guide, or control,the relative motion of a cutting tool, and the work operated uponthrough the agency of a suitable perforated tape.

Another object of this invention is to automatically manipulate certainadjustments of a suitable machine, which are ordinarily operated by handor by semiautomatic means, thereby producing a fully automatic device.

Fig. 1 is a diagrammatic end view of a manual punch.

Fig. 2 is a diagrammatic end view of a duplicating punch.

Fig. 3 is a diagrammatic end view of a tape senser.

Fig. 4 is a diagrammatic end view of a counting punch.

Fig. 5 is a schematic view of a fragment of a blank tape showing thelocation of each and every possible perforation and a graphicclassification of the possible perforations.

Fig. 6 is a View of a tape fragment showing a series of perforationsthat occasionally appear in actual operation of the machinery describedherein showing an interpretation of certain of the perforations.

Fig. 7 is a detached fragment of Fig. 6 showing only four perforationsand an interpretation thereof.

Fig. 8 is a view of a tape fragment showing a modified arrangement ofperforations, and, for the sake of clearness, the modified form containspractically the same information as that of the tape fragment of Fig. 6.

Fig. 9 is a combined side view and mid-section of a senser with someparts omitted for the sake of clarity.

Fig. l0 is a digrammatic exploded view of a pair of sensing pins withtheir connecting rocker arm.

Fig. 1l is a fragmentary irregular section showing the arrangement oftape driving sprockets and the switch operating mechanism of a tapesenser.

Fig. l2 is a sectional view of a duplicating punch showing the tapefeeding sprockets, presser rolls, etc.

Fig. 13 is a sectional View of a duplicating punch corresponding to atypical section through approximately the middle of the machine.

Fig. 14 is a diagrammatic conventionalization of the tape reel mechanismshowing certain switching mechanisms that may be associated with thetape reeling mechamsm.

Fig. 15 is similar to Fig. 14 with the parts in a diiferent position.

Fig. 16 is a combined side view and section of a tape feeding drum ofthe tape looper mechanism.

Fig. 17 is a highly diagrammatic view showing a pair of sensing pins innormal position, whereby the tape may be fed Without interference.

Fig. 18 is a diagram similar to Fig. 17 showing one of the two possiblepositions of the sensing pins during sensing.

Fig. 19 is a diagram similar to Fig. 18 showing the other possibleposition of the sensing pins during sensing.

Fig., 20 is a conventionalized representation of a sixteenth orderAbelian group which is isomorphic with the adopted perforation system ofthe tape as well as an isomorph of the differing positions of thesensing pins of the electric currents in certain circuits, etc.

Fig. 2l is an exploded perspective View of fragments of the elements atone end of a sensing carriage showing the mode of assembly.

Fig. 22 is a schematic circuit diagram o'f a polyphase selsyn connectedto a gang switch which switch in turn has its contacts connected to tapson a single transformer, some only of the actual connections beingshown; nevertheless, an obvious key, or code, clearly indicates theco'mplete connections.

Fig. 23 is a schematic circuit diagram of a polyphase selsyn connectedto single phase transformers which is isomorphic to the diagram of Fig.22.

Fig. 24 is a schematic circuit diagram similar to Fig. 23 having fewerswitches for obtaining substantially the desired results.

Fig. 25 is a conventionalized timing diagram for machines constructed inaccordance with this inventio'n.

Fig. 26 is a fragmentary end view of a machine having certain featureswhich may at times be desirable.

Fig. 27 is a fragmentary side view of a tape feeding sprocket andpresser roll of the type shown in Fig. 12.

Fig. 28 is a fragment of a contour generated by a machine tool with thecontrol mechanism disclosed herein, the said co'ntour being very highlymagnified so as to show characteristics not apparent except under amagnifying lens. i

Fig. 29 is an end view of a tape feeding sprocket and presser roll inproper relation to either a sensing chamber or punching chamber showingthe expedients utilized for overcoming certain problems involved in thefeeding o'f strips which are provided with marginal feed perforations.

Fig. 30 is a fragmentary view of one of the plates of either a sensingchamber or a punching chamber showing certain of the refinements of Fig.29.

Fig. 3l is a View similar to Fig. 29 containing additional refinements.

Fig. 32 is a diagrammatic view of a notched slide corresponding to a setof perforations which is used in the manual punch or in the countingpunch instead of a previously punched tape.

ARRANGEMENT OF KALKULEX UNITS It has been pointed out in the citedapplications for patent that a Kalkulex machine can be constructed ofcompatible Kalkulex units tailored to, lit into a particular applicationof the routine to be practiced. In general, the separate Kalkulex unitscan be viewed as an assortment of standard fittings which can beassembled into a complete machine by a process o'f assembly simulatingthat of erecting prefabricated dwellings, prefabricated ships,prefabricated furniture, etc. A few representative assemblies are showndiagrammatically in Figs. 1, 2, 3, and 4. In these diagrammaticrepresentations, Fig. 3

g may be called a senser for it is assemblage of Kalkulex unitsprimarily adapted to sense the perforations in a perforated tape, thento convert the said perforations into mechanical displacements symorphicwith the said perforations, then to close and open prearranged groups ofswitches for transforming the mechanical displacements into electriccurrents to correspondingly operate a very simple form of an evaluatorfor operating the controls of some machine, as for example, a profiler,a lathe, a pulp digester, or other suitable device. The diagrammaticrepresentation of Fig. 2 may be called a duplicating punch for theobject to be attained is that of duplicating an old or worn perforatedtape. The general operation of the duplicating punch is much like thatof the senser except that instead of controlling the switches of anevaluator, it gags punches for determining the location of the holes tobe perforated. The diagrammatic representation of Fig. 1 is much likethat of Fig. 2 except that the perforated tape sensing mechanism isreplaced by a series o'f'manually operable slides for controlling thestated punch gags. The diagrammatic representation of Fig. 4 isY similarto that of Fig. 3 except that the manually operable slides are operableby preselected gear train.

The senser is particularly useful for controlling machine tools,chemical devices, or other devices that are to be operated in accordancewith a determinable routine or cycle. The duplicating punch is primarilyuseful for replacing old or worn tapes by new ones. It is to beunderstood that a duplicating punch may make a new tape from aprearranged sequence of tape fragments. For example, suppose one hastape fragments corresponding to straight lines, circular arcs,hyperbolic arcs, etc. It is easy to understand that suitable po'rtionsof these fragments may be joined together to form a new contour. Thepiecing of such fragments is particularly useful in template work. Themanual punch is very useful for constructing perforated tape fragmentscorresponding to some special curve. Thus, it may be required that aportio'n of a contour to be profiled is a portion of an arc of acatenary, or a portion of an arc of a tractrix, etc. Some of these arcsmay require some tedius computations as well asA tedius handmanipulations. An operator of the manual punch may be given tabular datacorresponding to' such arcs, and, by a proper manipulation of the cams,a short length of arc may be readily constructed as a tape fragment. Thecounting punch is intended for constructing relatively long fragments bya process analogous to antidifferencing. It is particularly useful forcon- Structing relatively long fragments corresponding to straight'lineso'f a predetermined slope, tape fragments lc :orre'sp'onding to camshaving slowly varying curvature, etc. The -fragments constructed by themanual punch, or by the counting punch, or both, may be pieced togetherto form a master tape for the duplicating punch, whereby one longcontinuous tape can be constructed which represents a contour built upof individual fragments. The foregoing descriptions of therepresentative four machines include suicient mechanism for construcingperforated tapes corresponding to' almost any conceivable articleA to befashioned by a machine tool, or to almost any conceivable programassociated with a chemical process, or other applications of theprinciple that will readily occur to anyone skilled in the art to whichthis invention pertains.

Eachl ofl these machines contains a main drive; and some of theV punchesmay have an auxiliary drive instead of the more complete mechanismdisclosed in the cited Kalkulex applications. 4This is true becauseY ofthe degraded symmetry of most of the Kalkulex units used herein. Thesenser andthe duplicating punch are provided with a tape looper-whichsomewhat remotely simulates the looper usedon moving picture projectors.The function ofthe looper is to form a short loop of tape through thesensing, mechanism so that the mass of-tape moved by an amigasintermittentiy operating tape feeding mechanism is substantially aminimum. Both the senser and duplicating punch are provided with asensing Kalkulex unit which includes a tape chamber and intermittenttape feeding mechanism. Each of these machines is provided withtranssetters of an elementary type. All the mentioned machines areprovided with a transverting Kalkulex unit for converting the movementof sensing pins into a suitable mechanical displacement for governingthe operation of switches or for gagging punches. Both the manual punchand `the counting punch are provided with introducing Kalkulex unitswhich may be likened to a keyboard or an equivalent thereof; thismechanism takes the form of a series of manually operable slides of camsfor controlling the positioning of the punch gags. The senser isprovided with an elementary electrical type of evaluator instead of amechanical evaluator.

It is ,to be understood that other Kalkulex units than thosespecitically mentioned may be included in any of these machines if theexigencies of a particular situation should demand the presence thereof.This matter will be touched upon hereinafter.

FRAMEWORK The framework, as a whole, for several variant forms of themachines including the present invention, is shown in Figures 1, 2, 3,and 4. As in all Kalkulex machines the framework is tailored forparticular exigencies; the frames to be described are particularlyadaptable to the simple devices fully described herein. Each machine maybe viewed as consisting of two pairs of stacks of plates, one stackbeing identified by a, the other by b. These two stacks are separated bya spider frame e, and attached to each stack of plates there is abearing frame d, which frame may sometimes be attached to stack b.Elements a, e, and d are firmly connected together by a pair of dowelbolts f at each end of the stack a. In a similar manner, the partsadjoining the stack of plates b are connected by dowel bolt g. This modeof construction forms a simple and convenient method of attaching thecomponents of a machine together. The use of dowel bolts for theseconnections has the added advantage of correctly aligning all parts asan incident to the assembly of the mechanism, for the said dowel boltsdetermine iiducial planes for accurately and practically aligning theframe as a whole as well as properly locating certain carriages, sensingelements, etc., as will more fully appear hereinafter.

The stack of plates a constitutes supports, bearings, and housings forthe sprocket wheels and friction rollers which feed the tapeintermittently. They also form the top and bottom of the tape sensingchamber. The stack of plates b has a similarv function for the punchingof a fresh or new tape.

The spider frame e is a connection between stacks a and b, and itcontains ball races for supporting the sensing -carriage 30, and the gagcarriage 20. The frames e may be used for additional purposes such assupporting frames for a switching assembly for one or more evaluators asfin the case of the senser of Fig. 2, or other desirable adjuncts.

The bearing frame d is used primarily as a support for the extreme endsof the main shaft 10, or as a support for the bearings of the auxiliaryshaft 11. These frames also contain half of the bearings required -forthe reel driving shaft 51 (see Figs. 14 and 15).

At times, it is desirable .to have a looper mechanism for graduallytransferring the tape from a supply reel to a storage reel. The looperframes h consist of a pairv of castings having a large number ofrecesses, grooves, etc., therein for supporting the mechanism of thelooper. The frames h are constructed so that lthey iit between thecastings d; they are connected together by the bolt j, and fastened tothe castings va', by the bolts k. The rames h, with their containedmechanism, form a single unit which may be added to or removed from themachine as a complete looper mechanism.

The looper may be correctly viewed as the tape handling mechanism ofcertain Kalkulex units, as for example, sensers, punches, formulators,printers, or the like.

The main driving motor M (shown schematically as a circle) may be placedon the top of the looper castings h, or in some other suitable place.The motor M may be connected to the shafts 10 and 11 by any suitablepower transmitting mechanism such as the gears m, the shaft n, and thegears p. The shaft n may be supported by suitable bearings (not shown)mounted on the castings d, or in any other suitable manner.

The mechanism disclosed herein comprises devices for sensing thepresence or absence of perforations in a tape. To those not skilled inthe practical use of such devices, it may seem that the mechanismsdisclosed are overgenerous in size and superabundantly endowed withstrength for eifecting such a simple operation. Machines of this typeshould function reliably with a minimum of service, as well as operateat speeds that are extremely high as compared with the distantlyanalogous machines of the prior art. Among the compelling factors whichcontribute to the apparent massiveness are the following: These devicesare constructed largely of mere stampings and die castings. There arecertain dimensions which must be reasonably accurate. This condition ismost readily attained by an apparent massiveness. Again, certainelements, and in particular, the sensing needles, must act gently uponthe tape and there must be no undue strain on the tape when certainneedles fail to find a perforation. This requireemnt also calls forreasonably accurate dimensions which must be maintained over longperiods of time. This condition is most readily met by providing verylow mechanical stressesin the operating parts. This is particularly trueof bending stresses and torsional stresses. The requirements of the lowstress conditions dictate relatively large and massive carriages forcarrying the sensing needles, and the latter call for relatively largeshafts which in `turn call for correspondingly massive bearing supportsand housings. Alignment must be maintained on both sides of a tapechamber; this condition is most readily satisfied by generouslyproportioned dowels and elements aligned by the said dowels. Thisrequirement results in very generously proportioned tape chamberelements. Other conditions will appear as the detailed descriptionproceeds.

MAIN OPERATOR The term, main operator, includes the principal mechanicaldriving elements of the machine, and strictly also, a source ofelectrical power for energizing the driving motor and for energizingcertain portions of the selsyn-evaluator system.

The source of electric power is merely the usual service mains. Each ofthe machines diagrammatically illustrated in Figures l, 2, 3, and 4 isdriven by a conven ltional form of electric motor M which is connectedby suitable gearing to the main shaft 10 or to the shafts 10 and 11 asthe case may be. The mechanical connection between M and the shaft 10 orthe shafts 10 and 11 may be of any well known form and it is shown asappropriate sets of spiral gears on a vertical shaft n, for drivingshafts 10 and 11. It is usual, in perforated record controlled machines,to have a friction clutch between the driving motor and the main driveshaft or shafts, as the case may be. This friction connection may haveany desired form such as a disk clutch or a belt. Neither of theseconventional devices is shown in the drawings, for the mode of operationis both well known and very commonplace. As a matter of interest, themachine disclosed herein, when operating at normal speeds, emits a soundstrongly simulating that of a domestic sewing machine. v I

The shaft 10, is shown in part in Figures l, 2, 3, 4,

7 9,111, 12, 13, 14, and 15. TheV description of the functions of themain shaft'can -be readily understood by referring to Fig. 9. Rigidlymounted on one end of the mainshaft 1t), is one of the spiral gears p,for turning Ythe shaft 10. If desired, there may be a spiral gear p,

at each end of the main drive shaft 10 as is well understood in manyarts, and the driving motor may have a double connection thereto. Thisconstruction is advantageous if the machine `is to operate upon a verywide perforated tape, for this type of construction will minimize theundesirable effects of an appreciable torsionY on a long shaft.

Rigidly mounted at the middle of the main shaft 10 is a gear 14 fordriving the looper. The gear trains driven by the gear 14 will bedescribed in detail under the heading Looper. Near each end of the mainshaft, there -is rigidly mounted an eccentric and Geneva driver assembly18, Fig. 9, comprising a pair of mutually opposed eccentrics 16 and 17with a Geneva driver 18 between them. The eccentrics 16 operate links 19for reciprocating the gag carriage 20, and the eccentrics 17 operatelinks 29 for reciprocating the sensing carriage 30. Each of thesecarriages will be described in detail under appropriate headingselsewhere herein. The Geneva drivers 18 are used for intermittentlyfeeding the tape through the sensin@7 chamber, or through the punchchamber, or both, as the case may be. The construction of shaft 11 may,for convenience of manufacture, be identical with shaft if). The gagcarriage 20 and the sensing carriage 50 may be driven frornrthe shaft 11if desired as is shown in Fig. 1. Again, the sensing carriage 3i) may bedriven by the shaft 10, and the gag carriage 20 may be driven bytheshaft 11. The possible arrangements for reciprocating the carriagesare shown in Figs. 1, 2, 3, and 4. Such wide choices are characteristicof all Kalkulex machines. In every case, the looper, when present, isdriven by shaft 10. In the case of punching, the newly punched tape isfed by shaft 11 through the appropriate Geneva drivers 18.

The relative timing of the various elements driven by the main shaftwill be more particularly described under the heading Timing andcontrol.

LOOPER The looper has several functions, which may be tabulated thus:

(1) Keep the tape tautv as it is unwound from a supply reel.

(2) Feed the tape gradually from the supply reel.

(3) Form a loop in the tape prior to entrance to the sensing chamber.

(4) Feed the tape intermittently through the sensing chamber.

(5) Form a loop in the tape after it leaves the sensing chamber.

(6) Feed the tape gradually to a storage reel.

(7) Keep the tape taut as it is supplied to the storage reel.

(8) Contain mechanism for reversing the direction of tape feed.

(9) Contain mechanism for reversing one 'or more evaluators.

In the description of the looper, the gear trains will be describedfirst, then the path of the tape will be described, and finally thefunctions will be described in the order listed.

The description can be followed from Figs. 9, 13, and 14 with occasionalreferences to other figures which contain the specifically mentionedelement. The main shaft 10 has already been described as having rigidlymounted thereon a gear 14 near its midpoint. Meshing with gear 14 is asuitably supported gear 41 which is attached to a pair of pinions 42which in turn meshes gear 43. Reference to Figure 13 shows that thesegears and pinions are at about the center of the machine. Gears 43 arefixed to shafts, the other ends of which have fixed thereto the reel.

pinions 44 which in turn mesh with an idler 45, which in turn meshesgears 47 integral with each cf two sprocket carrying feeding drurns49(see also Fig. 16).

Each sprocket carrying drum 49 (see Fig. 16) comprises a mid-cylindricalportion terminated by sprockets 47. The distance between the centers ofthe sprocket teeth is the width of the tape (see Figs. 5, 6 and 8)between the center llines of the square perforations near the margins ofthe tape, and the pitch of the sprocket teeth is the pitch of the squareperforations of the tape so that when the feeding drums are rotated,they will correspondinglyV feed the the tape. Each feeding drum hasintegrally attached thereto a gear 47 and a spiral gear 48 at each end(see Fig. 16). The cylindrical portion 49 at the junction of the spiralgear 48 and the web of the gear 47 forms the supporting journal for vanend of the feeding drum as is clearly indicated in Fig. 16. The spiralgear 48 of one feeding drum meshes with a mating spiral gear 50 (seeFigs. 14 and 15) fixed to the shaft 51. At each outer end of shaft 51,there is a spiral gear 52 rigid with said shaft. Each gear 52 mesheswith a companion spiral gear 53 fixed to the shaft 54 of the tape reel55. Each tape reel 55 is flictionally attached to its shaft. Thefrictional adjustment is such that the frictional connection will s lipwhen the tape is suiiiciently taut to avoid undesirable festoons and/orbunching on The direction of rotation of the reels 55 is such that theyalways tend to wind up the tape as can be easily seen by followingthrough the gear trains of Figs. 14 and 15. The shaft 51 is normallymovable along its axis so that said shaft is resiliently held in eitherof the two possible positions.

The mentioned resilient means for holding shaft 51 may be used for theadditional purpose of reversing the motor M, and other desirablefunctions. This mechanism will be fully described elsewhere herein.

The path of the tape 58 and its directions of movement are best seen inFigures 14 and l5; these two figures are copiously supplied withdirection arrows so that inspection thereof is a sufficient descriptionof functions l and 7 of the looper which have been specifically setforth at the beginning of this article.

An -inspection of the arrows in Figures 14 and 15 shows that the tape ispulled from the supply roll by one of the feeding rolls `49 against thetendency of the reel to wind the tape. It therefore follows that thetape should tit snugly about the feeding roll 49; this is effected by afriction roll 56 which is resiliently pressed towardsthe roll `49, theamount of the pressure being sufficient to insure that the describedaction occurs. The feeding rolls 49 travel at a speed corresponding tothe length of the briey described intermittent feed of the tape, duringeach rotation of shaft 10. The requisite speed for the feeding drums isattained by the gear train beginning with gear 14 on themain shaft andending at the feeding drums.

After the tape passes about halfway around a feeding drum 49, it is fedoutwardly by the combined action of 49 and a friction roll 57 to form aloop 58 prior to entering the sensing chamber. 'Ihe function of the loop58 corresponds closely to the loop used in moving picture projectionmachines; that is, there is a short length of tape having only a smallmasswhich is quickly and intermittently fed through the sensing chamberby suitable intermittently operated sprocket feeding means.

The intermittent tape feeding means comprises two pairs of Sprockets 6i?(see also Figs. l2, 13, 26, 27, 29, and 31); each sprocket of the pairis fixed to a shaft 61 in such a location that its teeth can mesh withthe square holes at the edges of the tape, and further, the tape is heldagainst the pitch drums of the said sprockets by suitably arrangedpresser rolls 62. Fixed at one kend of one of the shafts 61 is asuitable Geneva star wheel 59 which meshes with the Geneva driver 18.The Geneva driver 18 at the other end of the main shaft serves to gdrive the other pair of feeding sprockets. It is a matter ofindifference which of the shafts 61 is driven by a particular Genevadriver so long as the proper relative timing -is attained, as willappear in more detail elsewhere herein. Here is another example ofdesign choice in Kalkulex machines.

The intermittent feed suddenly enlarges the discharge loop, and thisenlargement is gradually diminished by the assembly of rolls 57 and 56with feeding drum 59 f the output end of the tape, thus feeding thesensed portion of the tape, through a loop, gradually to the storagereel 55, and, due to the frictional drive of the storage reel 55, thetape is kept taut.

This completes a brief and general description of the functioning of thelooper. There are some interesting and novel features in the mechanicalconstruction of the looper. The principal part of the looper comprisesthe above described gear trains and tape feeding rolls and sprockets.All of the parts are mounted on, or between, two bearing castings d (seeFigs. l, 2, 3, and 4) which are utilized in duplicate. Each castingl dcontains an end bearing of the main shaft 10. This casting has certainrecesses therein for clearing the links which surround the eccentrics 16and 17. Other recesses accommodate the spiral gears 50, vand stillothers form clearance recesses for other elements.

The castings h, which also appear in duplicate, support all of the rollsy49, 56, and 57 as well as a portion of the gear train driving these`rolls. Provision has been made for removing the said rolls 47, 56, and57, thus completely removing the looper mechanism except theintermittently driven sprockets 60. Reference to Figs. 2, 3, and 4'shows a like arrangement for supporting the shaft A11.

The looper mechanism comprising the sets of rolls 49, 56, and 57, thetape reels and the drives therefor, is in the nature of a iiexible stripfeeding and handling mechanism; it is not an absolute necessity for thecorrect and proper operation of the machine. lt is, however, a verydesirable adjunct for the perforated tape is relatively fragile, andit'could be easily damaged accidentally if there were no specificprovision for keeping those portions of the tape not being sensed in aconvenient and reasonably compact fonn.

A careful inspection of the looper mechanism will show that severaladditional functions may be performed if desired. As obvious examples,the looper as a whole is disconnected from the 'drive shaft if it isslightly elevated with respect to the main shaft. Again, a double trainof gearing extends from the center of the machine to the feeding drums59. `If desired, one train can be omitted, or there may be a separatetrain for each feed roll 59 so that each feed roll can be independentlydriven. If desired, each feeding roll 59 can be arranged to be drivenmanually by the provision of suitable manipulative knobs. None of thesemodifications are shown; they are mentioned to call attention to thepossibility of effecting certain operations not specifically shown.rIhese possibilities fairly illustrate certain of the inherentmodifications which may be more or less readily incorporated intoproperly designed Kalkulex machinery.

REVERSING THE TAPE At times, it is necessary to reverse the direction ofthe tape feed; thus, when the supply reel is empty and the storage reelis filled, it is necessary to feed the tape relatively backward. Thismatter has been briefly considered under the article Looper where thegear train which drives the reels was fully described in connection withFigures 14 and l5.

Mounted on the shaft 51 is one or more double level collars 120 and 121.The collar 121 is specifically associated with the reversing of theSenser driving motor- M and with the mechanism for stopping the saidmotor M when the end of the tape is reached. The said col-A lar 121determines the position of leaf spring 125 which in turn controls thetongues of a pair of single throw double pole switches. The oppositepoles of one of the said switches are connected to the terminals of thedouble field windings of the motor M. The tongue of said switch isgrounded, and the midpoint of the said double iield windings of themotor M is also indirectly grounded through a pair of sensing switchesSD and Sr. The tongue of the other double pole single throw switch isalso governed by the spring 125 in accordance with the usual manner ofoperating multiple tongue switches.

Consider the position of Fig. l5. Tracing the circuit from groundthrough the switch tongue, then to the closed contact, then to half theteld windings, then to the eld midpoint, then through SD, then throughthe switch tongue, then to the closed contact of switch and finallythrough the voltage source to the ground. Dur ing the major part of thetape feeding, switch SR is also closed so that there is a doubleconnection to the source of voltage. When the end of the tape isapproached, the switch SD is opened, and the motor circuit is broken.When the time for restarting has arrived, button 124 at the end of shaft51 is pressed in, and the motor starts agaln.

'Pressing of said button 124 mechanically relatively .reverses thedirection of the reel drives as has been described under Loopen Thismovement also causes a reversal of the tongues of the two switchescontrolled by spring 125 so that a circuit can be traced, thus: groundthrough switch tongue to the other half of the second single throwdouble pole switch, thence to switch tongue, thence to SR, thence to thevoltage source, thence to the ground, thus completing the circuit andstarting the motor M. Shortly thereafter, the switch SD closes, but suchclosure merely Ibridges a closed contact and hence does not alter thecircuit just traced.

When the end of the tape is reached, the switch SR opens, thus breakingthe circuit of the motor M and stopping the machine. When the shaft 51is again shifted, the two single throw double pole switches have thepositions of the iirst circuit traced. The motor starts because switchSD is closed. Shortly thereafter, SR closes also, thus bridging anotherwise closed circuit.` From the two circuit tracings, it is seenthat the machine always stops when the end of the tape is reached, andsuch stopping occurs by virtue of the opening of switch SD at one end ofthe tape. The switch SD is controlled by one set of perforations, andthe switch SR is controlled by another set of perforations. These setsof perforations may be sets 5 and 6 of Fig. `6 or any other desired pairof sets. Ordinarily, the two said sets of perforations occur betweencolumns I and II of Fig. 6.

The collar 120 may control one or more double throw double poleswitches. The tongues of such switches may be connected to a transformercoil (e.g., the sine secondary of Fig. 24) and the poles thereofconnected to a pair of phases of the selsyn as shown' in said Fig. 24.This reversing switch may be used to ensure that the cutter will alwaystravel in the same direction (say, anticlockwise) around the contourirrespective ofthe direction of tape movement. Obviously, there may be aphase interchanging switch for eachv selsyn, as shown in Fig. 24 at PR.

THE TAPE the tape as a physical entity and tion of all perforations isshown in Fig. 5. The tapel feeding is accomplished, in part, by sprocketteeth meshing with the substantially square holes near the margin, Themethod of feeding and the mechanism associated of information win befuny de' and this is the sole function of these holes.

therewith have been fully described in the article Looper?? All of theremaining circular perforations are used for recording information, orthe data requisite for the proper operation of an evaluator or punch asthe case may be. Each tape inherently contains a plurality of sets ofpossible perforations. One set of possible perforations comprises theZig-zag series of full and dotted perforations adjacent to a line ofsquare holes; one such series is identified asset l in Figs. and 6.Another set of possible perforations is that adjacent to the firstmentioned zig-zag line, identified as set 2 in the cited figures; and soon, across the width of the entire tape as indicated in the drawings.The specific fragment illustrated shows l2 sets of possibleperforations. It is to be understood that tapes may be either Iwider ornarlrower than the specific example illustrated so that a tape cancontain either more or fewer sets of perforations. In extreme cases, thetape may contain 30 to 40 sets of perforations, that is, 21/2 to 4 timesas wide as those specifically illustrated in Figs. 5, 6, and 8.

For convenience of explanation, each set of possible perforations isdivided into two classesthe first class is identified by full circles,and the second class is identified by dotted circles. Further, eachclassis divided into two speciesthe first species is identified byY fullcircles, and the second species is identified by circles containing acentral dot.

The object of perforating a tape is to permanently recorded data thatcan be interpreted by suitable, and preferably very simple, machinery.It is reasonable to suppose that a simple and convenient method ofmachine sensing is one such that one or the other of two possiblelocations will be found lby a pair of interconnected sensing needles orpins. Such a system is fully disclosed in the cited Kalkulexapplications, and it is also the system adopted here. One or the otherof two bits of information is identifiable with such a system. Forexample, suppose the data to be recorded by a possible set ofperforations (i.e., the e:above mentioned zig-zag line) (l) The presenceof a symbol (say, an is present), or (2) The -absence of a symbol (sayan is absent);

then, the rst bit of information may be recorded by a full circlewhereas the second bit of information would be recorded by a dottedcircle. To the uninitiated, this may appear, as a first impression, tobe a sort of supernumerary method of recording data. When contrastedwith the prior art, this first impression is correct for the prior artrecording would take the form of the presence of a perforation tocommemorate the presence of a symbol, and the absence of a symbol (orperhaps, vice versa).

Forjemphasis, it is repeated that the supposed information and theabsence thereof, are each represented by a perforation-but, theperforations are in different locations, thus accounting for the abovementioned two species of per-forations. In a sense, this is a dualsystem, and further, it rnay be viewed as characterized by the samegrade of symmetry as that existing between an object and its mirrorimage, or its mirror image combined with a glide distance. To restatethe system of recording in other words, the presence of a symbol isrecorded by a perforation in a predetermined location; whereas theabsence of a symbol (or the existence of the specter, or image of asymbol) is recorded by a perforation which may be correctly viewed asthe mirror image (perhaps with a guide) of the first mentionedperforation. In terms of the technology of the art or science ofsymmetries, the recording of data has at least a monoclinic grade ofsymmetry.

For the purposes of further illustration of the system of yrecordingdataby perforations, Fig. 6 shows a fragment of. a perforated tapecontaining the followinginformation listed in Table A:

Va corner, then turning the corner.

For the sake of contrast, the presence of a perforation is indicated bya solid black circle for each species of perforations. For the purposesof identification with the table above, Fig. 6 has a double array ofnumerals from 0 to l5 inclusive near the margins of the tape.

Suppose one seeks to identify the item of information in Fig. `6; oneseeks the horizontal lines identified by the 9s. The array ofperforations corresponding thereto is shown in Fig. 7. One may identifythe two *s as the two perforations at the bottom of Fig. 7 and absenceof i"s, preferably the ghost or specter of "-"s (hereinafter calledspecter) as the two perforations at the top of Fig. 7.

It is easy to see, by a comparison of Figures 6 and 7 that the objectand specter in the latter figure are separated by an appreciabledistance, and further, that another object and another specterordinarily lie between the object and specter corresponding to 9.Referring to Fig. 6, it is seen that the object portion corresponding tol0 and the specter portioncorresponding to 8 lie between the objectportion and specter portion of 9. It is to be understood, as will bemore clearly seen hereinafter, that this arrangement merely comprises anillustrative example. fIn some instances, it may be desirable to havetwo object portions and two specter portions between the object andspecter portion of any entity. Such an arrangement is shown in Fig. 8.As a matter of interest, Figures 6 and 8 contain exactly the same data(except at the extreme top and bottom), yet they superficially appearvery different. Y

All of the other l5 different bits of information may be likewiselocated in Fig. 6. When Fig. 6 is compared with Fig. 5, it will be seenthat only half of the possible perforations occur in Fig. 6; in each andevery instance,v

there is either a perforation indicated as a full circle in Fig. 5, orthe specter of a full circle appears; but in no case does -both a fullcircle and its specter appear-always, it is the one or the other.

Returning to Fig. 5, it may be said that the possible perforations areindicated by full li-nes, and their specters appear as dotted circles.It is important to keep in mind the symmetry of perforations, for onecan say with equal truthfulness that all possible perforations areindicated in Fig. 5 by dotted circles, and the specters thereof areindicated by full line circles. This `dualism is of considerableimportance in the sequel and in the functioning of the evaluator to bedescribed later. Considerable stress has been laid on the symmetries ofthe tape and the system of perforations used, for this symmetry is ofthe utmost importance in the proper functioning of the device disclosedherein. There are a large number of symmetries in Table A which are ofgreat importa-nce. Let each 0 in Table A be regardedA as the specter ofan absent Now, Fig. 7 has been identified by the numeral 9. If thearrangement identified as 6 'be found in Table A and also in Fig. `6, itwill be seen that they are mutually related as object and specter. Alittle further study of Table A will show' that, if a mirror is imaginedas placed between 7 and 8 of Table A and also between l and 0, then thatpart of Table A on one side of the supposed mirror is the specter ofthat part on the other side of the supposed mirrors-further, this is amutual relationship.

Needless to say, exactly the same relationships exist in Fig. 6, butthese mutual object and specter relations are not as patently evidentbecause .there is a relative glide between object and specter. A littlestudy of Fig. 6 will, however, quickly reveal that a number of obvioustranslational symmetries appear. Some of these translational symmetriescan be most readily seen by occulting all of the sets in Fig. 6 exceptone of them.

These translational symmetries are most evident for sets 1, 2, 7 and 8.The combinations of sets l and 2 also show a slightly more complicatedsort of translational symmetry. With a little practice, a similarsymmetry can be seen when three sets are viewed with the exclusion ofthe others. These symmetries i-n the tape itself are very importantfactors which contribute much to the simplification of the mechanicalsensing mechanism to be described in detail hereinafter.

These translational symmetries also appear in Table A. If the last lineof Table A is supposed to be deleted, then mirrors can be supposed to beplaced between 3 4 and ll-l2, as well as the first supposed set. Again,there is the mutual relation of object and specter on each side of thesupposed mirrors. This same process may be carried out by supposing boththe third and fourth rows of Table A deleted, then supposing theexistence of mirrors located at proper positions; again like resultswill follow. Needless to say, there is -a corresponding symmetry in Fig.6 with glides superimposed thereon. Enough has already been said toclearly indicate the existence of conspicuously phenomenal symmetries inthe system of perforations, and it is accordingly proper to adopt acorrect technical terminology therefor.

In the technology of finite periodic groups, the system of perforationsadopted is a mere isomorph of a simple sixteenth order Abelian group. Itwill be assumed that those skilled in the art or science to which thisinvention belongs are familiar with the science of the elements offinite groups. To such persons, the following list of isomorphs of the16th order Abelian group are either self evident, or will become so asthe detailed description proceeds.

Table B SOME ISOMORPHS OF AN ABELIAN GROUP (l) The code of perforationscorresponding to the information listed in Table A.

(Z) The perforations in the tape fragment of Fig. 6 or of Fig. 8.

(3) The r16 sixteenth roots of unity.

(4) The sixteen fourth order non-singular diagonal matrices constructedwith -11 and -1 as the nonevanescent elements.

(5) Any sixteenth order gyric group.

(6) Any mechanical displacements isomorphic with the perforations ofFig. 6 or of Fig. 8.

(7) Any electrical switching system lisomorphic with the perforations ofFig. 6 or of Fig. 8.

(8) The complete residue system (modulo v16).

(9) Any sixteen step, two way ratchet, sixteen step selsyn generator,etc.

(10) The alternating currents in the selsyns mentioned in isomorph 9.

(l1) The currents in the `switching system mentioned as isomorph 7.

Much of the remainder of this specification deals with the listedmechanical and electrical isomorphs of tli mentioned Abelian group. Itmay be proper to point out that isomorph 8 is exactly the last line ofTable A, and it is also the array of numerals at the edges of the tapefragment of Figures 6 and 8. In the language of simple arithmetic, thearrangement of perforations of Fig.- 6, and Table A as well, is a merelisting of symbols more or less appropriate to a bioctagesimal system(sometimes known as a sexadecimal system) of numera tion (e.g., thefamiliar sixteenths graduations of meas-j uring rules). The use .of suchsymbols for pencil and paper computations might appear to be extremelyawkward and clumsy, yet for appropriate machinery, they may serveexcellently. As a matte'of interest appro`- priate symbols can -be usedto greatly facilitate pencil and paper computations, and such symbolsare mere obvious isomorphs of those illustrated. l

Again, isomorph 5 is little, if any, more than the application of asexadecimal system of measuring certain rotational steps (e.g., thefamiliar compass card divided into sxteenths). Isomorph 3, particularlywhen viewed in the light of the vector representation of alternatingcurrents, is merely the algebraic method of representing Table A; andisomorph 4 is substantially the same mode of representation byeliminating the imaginary expressions that appear in the sixteenth rootof unity.

Reasoning from these statements, it is easy and proper to infer that theremaining isomorphs are also correct 4because of the specificlimitations of the phraseology used in defining the isomorphs.

It is to be understood that the bioctagesimal system described is merelyan illustrative example. The slightly simpler octagesimal (i.e., havinga radix hal-f of the radix of a sexadecimal system) system or theslightly more complicated tetraoctagesimal system (i.e., having a radixwhich is twice the radix of a sexadecimal system) may have been chosenas illustrative examples. In machines' actually constructed and used,the bioctagesimal system has been adopted, for the limits of accuracyimposed on the work to be accomplished are such that the system amplysufiices. With coarser limits, a lower order system may be used; withfiner limits, a higher order system may be required.

Suitable tapes may be made of a variety of materials. Thus, a good gradeof kraft or long fibered sulphite paper is satisfactory. Severalplastics serve excellently, as for example, certain of the cellulosebase plastics such as cellulose acetate, cellulose nitrate, or the like.Certain impregnated fabrics are also good, such as cambric or poplin orVoile impregnated with certain of the rubber derivatives (e.g.,Pliofilm, Tornesit, etc.). If extreme durability is desired, the tapemay be made of metal such as thin steel, -a hard brass, berylliumcopper, etc. The

choice of material for the tape is largely a matter of user preferenceas well as the amount of use that the' tape may be required towithstand. Acetate tapes have been found to be reasonably satisfactoryfor experimental tests.

In the specific invention disclosed herein, four sets of perforations,as for example column I or column II of Fig. 6, are used for controllinga selsyn through an evaluator. The specific example shown is adapted tocontrol two selsyns, and two sets of perforations are reserved l forother desired purposes. It is to be understood that tapes of any desiredwidth may be used for controlling a corresponding number of selsyns, orother desired devices. It is also to be understood that more sets ofperi forations (e. g., five or six sets) may be used for controlling aselsyn, as will be more fully described under the heading Evaluators Thetape is used `for governing the rotations of the evaluators, and suchrotations consist of more or less lengthy rotations in either of the twopossible directions (forward and backward). Each of these rotationscomprises an integral multiple of some angular displacement, l

as will appear more fully hereinafter. Therefore, the perforations inthe tape consist of corresponding series of consecutive positions suchas the marginal numbering of Figures 6 and 8 clearly indicates. Indeed,:these two figures show the arrangement of perforations corresponding tothe path of a cutting tool approaching a corner and progressing onwardat substantially a right angle. The described motion consists ofpredetermined steps, each of a predetermined length. For lthe sake of anumerica-l example, suppose that the rotary steps consist of 1/16 of arotation and that the shaft which rotates 1/16 of a complete turn issuitably geared down so that an element (e.g., a milling machine table,a lathe carriage, a planer saddle, a boring bar, etc.) moves 0.002".Under this assumption, when theY tape perforations 7 (say) arecontrolling said element, then the said element will have a certainposition; when the next perforations 8 (say) are controlling, then saidelement will be moved 0.002 (forward, say, for the sake of a particulardirection) from the said certain position; had the next position been 6(say), then the said element would have moved 0.002" in the oppositedirection (backward). Looking at the tapes of Figures 6 and 8, it willbe seen that in the case of column I, the perforations progress(-forward, say) through successive steps to the symbol identified aszero, then progress in the opposite direction (backward, say) bycorrespondingv steps. In the case of column II, the progress is alwaysin the same direction. It therefore follows that the said tape fragmentsof Figures 6 and 8 represent a motion corresponding to a steadyprogression of an elementV in an east-west direction (say, for thepurposes of identifying a particular direction) combined with anorth-south direction (say) which finally reaches the point identifiedby zero, then a regression in southnorth direction, thus forming acorner.

The preceding description relates merely to straight lines having a 45slope. This example was chosen for explanation because of its extremesimplicity and frequent occurrence. In practice, other slopes occur.Thus, the illustrative tape fragment of Fig. 6 may have had column I asillustrated, whereas column II may have had a monotonous repetition ofthe same symbol. In that oase, the tape fragment would represent acutter going into ya notch, thenv backing out; thus such a tape wouldcorrespond to va cutter entering' a blank to form the notch 73 of Fig.10, then starting to back out. Again, column II may haveconsisted of avery fe'w different symbols (say, 6 repetitions of one symbol, 6repetitions of the adjacent symbol, etc.), then the tape would representa notch similar to 73 or Fig. l0 except that it would be u slightlywider lat the mouth. Again, the arrangement just described may havebeenV such that the arrangements of column I and column Ii wereinterchanged.y This would give identical results except that alldirections would ap pear as if rotated througha right angle. Again thesymbols may have been frequently repeated, etc. It is obvious that manyother possible combinations may have been shown. Many of them wouldresult in curved lines. Indeed, curved lines are commonly represented bypolygons of many short sides. This matter will receive furtheryattention later herein. From the foregoing, it should now be evidentthat the pe-rforations in the tape actually represent thefcoordinates ofa curve at substantially consecutive points,V `as for examplethey maybeI points separated by a chordal distance of approximately 0.002", orof Aany o-ther judiciously chosen distance compatible with the desiredaccuracy of cutting.

THE PHYSICS OF TAPEFEDING The feeding of -a tape through a sensing'orpunching chamber, particularly with theV above described mechanisrn, mayappear to 'bea very simple' and a readily understood mechanical action.LIn, practice, this action is surprisingly complex: Theprobleni isparticularly im'- portant because-the relatively fragile tape? shouldhave a reasonable length of useful life. It is the object of thisarticle to disclose the more important problems encountered in flexible`sheet feeding and some specific structures for solving said problems.There are a Very large number of patents disclosing exible strip feedingmechanisms; these patents, perhaps include/the entire gamut of the tapeand card controlled art. None of the prior art patents show more thanparticular solutions of only a few of the problems encountered in aproperly designed positive strip feeder.

Certain elementary, yet fundamental, facts relative to flexible stripfeeding are inherent in the action of hot sheet rolling mills. The usualrolling mill consists of a pair of rolls of substantially equaldiameter, and the diameter is large as compared to the thickness olf thesheet passing therethrough. The hot sheet passing between the rollstends to emerge from the rol-ls along the direction of the commontangent to the rolls. This tendency is accentuated by having both rollsof substantially equal diameter so that each roll has substantially thesame action on the surface of the metal. A like phenomenon is associatedwith the Common Wash wringer. Experiment will demonstrate that articlessuch las pillow cases, towels, etc., strongly tend to emerge from thewringer rolls in the direction of the common tangent of therrolls, andto maintain this direction :for an appreciablevdistance beyond egress.It is obvious that a iiexible sheet feeder should imitate both therolling mill and the wash Wringer.

lf the flexible sheet has a curling tendency (e.g., it is normallystored on a roll) the curl may be advantageously used to partially stripthe tape from the roll to which it may tend to stick or adhere the more.If there is no tendency to stick, then the curl may be used to partiallycounteract gravity and thus increase the normal tendency to follow thecommon tangent of the rolls.y Experience demonstrates that a web with acertain amount of inherent stiffness will be easier to manipulate than asleazy material. Sleaziness may be partially counteracted by using ahigher pressure or stronger nip between the rolls. Advantage can betaken of these simple and commonly known facts to design the doctorblade which aimost touches the rolls to support and guide the flexible`sheet after it emerges from the rolls, and guide it into the rolls. Ingeneral, the saiddoctor blade should approach the roll as closely `aspracticable, yet it must be at a predetermined distance from the commontangent of the rolls. A construction which can be attained in practiceis shown in Figures 29 and 3l. The said doctor blades comprise a chokingof the tape chamber in the immediate vicinity of the ingress and egressto the feeding' rolls, `and the length of the narr'olwest part of thechoke is yapproximately twice the circular pitch of the sprocket. If thetape yalways entered and emerged from the rolls'in the ideal fashion,the doctor blades would be useless; however, if the tape tends to departfrom the ideal, then the doctor 'blades will guide it towards the idealposition. The exact form and dimensions of the mentioned doctors islargely `a matter of trial and' error for differing tape materials.

Thus far, it has been tacitly assumed that the flexible sheet has nofeeding holes and that roll's areA at least as long as the sheet isWide. In practice,`V the feeding rolls nip `only the edges of the sheet,and there vare feeding holes near the edges (see Figures 5, v6,- and S).These constructional features modify the foregoing observations. Thesemodifications will new beV investigated.

The tapes of Figures 6 and 8 are provided with feeding holes near' themargin'. As a rria'tter of engineering construction, the materialbetween the more or less square holes simulates ya thin section of theteethof an ordinary rack or of a linkbelt; therefore, the feedingsprockets 60 (see Figures l2, l5, 19, 29, and' 3l) have gear teethWhich'properly meshthe mentioned simulated rack or linkbelt. Since theholes are punched, thev sides thereof are, at least theoretically,straight sided (see jdent to the punching operation.

of the corresponding roll surfaces.

17 Figures 29 and 3l) therefore, the tape should be viewed as a thinsection of a cycloidal rack at the pitch line and therefore the sprocket60 should be provided with the mating cycloidal odontoids, thusdelinitely fixing the shape, length, etc., of the sprocket teeth. Thefeeding rolls therefore take the form of cylinders of predeterminedlength with a narrow sprocket at the middle of the one roll and a likecylinder with fully shrouded teeth for the cooperating roll, as isindicated in the sectional view of Fig. 29. The pitch circles ofsprocket 60 and cooperating shrouded gear 62 have the center line of thetape as their common tangent. It is desirable to design the sprocketteeth as pointed, then relieve them so as to have ample clearance forthe teeth when first entering and leaving the holes in the tape. Thedescribed alterations are diagrammatically shown in Fig. 29 Where thefull lines indicate the actual shape used for the sprocket teeth and thedotted lines show the theoretical cycloidal teeth. In some cases, theteeth of the sprocket 60 are constructed `as mere circular arcs;analysis however shows that the teeth should be cycloidal; thus thedotted lines show the theoretical shapes when no allowance has been madefor deviations from ideal dimensions. It is usual to yassume Iavariation of about 0.3%-0.5% in dimensions. It is accordingly necessaryto modify the actual teeth so that the tips correspond to the shortestdistance and the thickness of the teeth yat the root circle correspondto the smallest feed perforation-whereas the tooth pitch corresponds to-a mean of the longest and shortest pitches on the tape. It accordinglyfollows that the correct tooth outline remains cycloidal, but that therolling circle becomes smaller. In practice, it has been found thatsprockets with involute teeth may be used provided that the pitch circlesubstantially coincides with the involute base circle. This is obviousinasmuch as the involute curve is perpendicular to the base circle atthe point of contact. It therefore follows that the involute teeth musthave a small clearance or relief below the base circle as indicated inFig. 3l. Since the involute curve is very sensitive near the basecircle, the desired results may be `approximately attained if thepressure angle atv the pitch circle is small (e.g., to 5). Alltheoretical involute tooth forms are decidedly inferior to properlyYdesigned cycloidal forms for tape feeding. Practically all of the holesin the tape are slightly bur-red as an inci- It therefore follows thatthe burr side of the tape should be the dedendum side; and, there should-be :a notch or pocket at the root of the sprocket teeth to receive saidburr (see Fig. 3l). In practice, this inference has been found to beapproxilmately correct; nevertheless, Ia few runs of the tape throughthe senser serve to remove the mentioned burrs Aas a fine dust, thusclearly showing a tendency of the sprocket teeth to grind or polish thetape feeding holes to smooth working surfaces. It therefore followsthat, Within limits, `a tape that-has been used for a time feeds betterthan a tape which has just been punched. It is therefore `desirable torun a newly punched tape through a tape feeding chamber ya few times toburnish the feeding holes before putting it in service.

This eifect can be best attained if the feeding sprockets havesubstantially the correct odontoid shape. Such an operation may becalled conditioning the tape.

When a feeding roll has been modified by including a sprocket, themating roll is correspondingly modified. It is preferable that themating roll have the form of a fully shrouded gear 62 (see Figures 29and 3l). The theoretical form is a mating gear whose addendum isslightly below the pitch line of the sprocket so that there will besuicient room for the tape between the dedendum of the sprocket and the-addendum of the cooperating roll gear as shown in Fig. 29; and the saidaddendum and dedendum surfaces should be cylindrical continuationsSubstantially perfect mating can be attained if the odontoids havecycloidal y contours. If the odontoids have an involute contour, the

perfection of mating can be only approximately attained. In practice, itsometimes suftices to merely groove the cooperating roll (see Figures l2and 27) so as to form a clearance for the sprocket teeth. The groovedconstruction `amply suiiices for the looper (see Figures l2 and 16). ltshould be clearly understood that this method `falls short `ofperfection. The manufacture of fully shrouded gears, in small quantitiesby conventional methods, is both difcult and expensive-hence, thedesirability of the described grooved construction of Fig. l2.

"Bhe general principle that the flexible sheet tends to follow thecommon tangent when passing between rolls with la nip is modied by thepresence of sprocket teeth on one of the rolls, for (except at the pitchline) there is a frictional force between the walls of the tape feedingholes and the sprocket teeth `whereby the tape will tend to cling to thesprocket instead of following the common tangent. This tendency can be,at least partially, nullilied by arranging the tape so that its inherentcurlingr tendency (due to being stored in coils-see Figures 14 and l5)opposes the friction on the sprocket teeth. Thus, referring to Figuresl5 `and 14, the tape should come from the tops of the reels as shown.Again, since the tape will tend to wrap about the sprocket (because oftooth friction), the cooperating rolls 62 should be made of a materialwhich has a slight tendency to stick to the tape. Again, the vabovedescribed mode of reducing the thickness of the sprocket teeth towardsthe addendum partially reduces the tooth friction `and thus reducessticking to the sprocket. Certain of the rubbers and some plastics if'frosted, or etched, have such properties. A proper balancing ofinherent curling, roll adhesion, sprocket tooth relief towards theaddendum, and nip can approximately restore the normal tendency of theflexible sheet to follo'w the normal path of coincidence to the commontangent. This balance can be readily obtained for short distances.Observation Iand experience indicate that such ydistances are of theorder of several times the tape,

thickness. It therefore follows that' the aforementioned doctor bladescan be separated from the rolls an amount corresponding to about 11/2 to2 times the tape thickness; and, further, the common tangent of the feedrolls should coincide with the center of the sensing chamber (orpunching chamber). In practice, the doctor blades can approach thesprocket to within about 1/z to :M of the tape thickness as isspecically shown in Fig. 29. This obtainable approach is desirable forslight imperfections and small burrs will then have ya less unbalancingeffect upon the normal tendency of the tape to coincide with the commontangent. In general, it is usually desirable that the punching chambershould be narrower than the sensing chamber, particularly along theZones where the tape is stripped from the punches in order to avoidnoticeable ridges or burrs about the freshly punched holes. Such chokingis shown in Fig. 29 where the mentioned zones have the folrn of mesas inthe vicinity of the punches. This desirable end may be attained byrequiring the stripper plate to have only a small clearance with respectto the punches. This end can be readily `attained by making the stripperplate and the die plate as duplicates. i

The desired nip between the rolls may be obtained in any convenientmanner. Preferably, the nip should be adjustable in the process ofmanufacture. Usually, it is not necessary to vary the nip after assemblytesting. One simple method of obtaining the desired nip is illustratedin Fig. 27. A spring well is provided in the plate a, and spider framee, for the said spring. A manufacturing adjustment is shown as a smallstack of disks at the lower end of the spring.

If the flexible sheet is very wide, it is sometimes desirable to providesome convenient roll with a double worm. This expedient is common inmany arts, and it is not specifically shown. When it is desirable toprovide such a double worm, it may be placed upon the rolls 47. vAs iswell known, such worms tend to prevent the formation Y i 19 of wrinkles,thus keeping the flexible sheet smooth at all times.

The foregoing description of doctor blades, clearances,

punching mesas, bearings for shafts 60, dowel holes, bell Vticularly forpunching) or die castings (particularly for sensing). Although theseelements have many irregularities or low mesas, they are simply producedby either process.

If the inherent curl of the tape is positioned as indicated in Figures14 and 15, the tape will tend to hump away from the sensing pins,particularly at the center of the sensing chamber as shown to anexaggerated degree in Fig. 25. Advantage can be taken of this tendency,for the sensing pins which Will fail to find a perforation will bestopped slightly before they would be if the tape closely hugged theupper wall (Fig. 25) of the sensing chamber, thus assuring the initialcontact of elements 80 and 81 (see Fig. 13), as will be moreparticularly described later.

When the teeth of the sprocket are foreshortened as indicated in Fig.29, they may serve the additional function as aligners when in theposition shown. When the tape is aligned, it should not be constrainedby friction. This end may be admirably served by forming a clearance atthe base of each tooth as shown in Fig. 31, and also attening thecooperating roll 62 at the brink of the depressions. The same end may beachieved by the use of proper cams (not shown) xed to the shafts 61 sothat said shafts are slightly separated when members 60 and 62 have theposition shown in Fig. 31.

SENSING UNIT The function of the sensing unit is to obtain mechanicaldisplacements isomorphic with the arrangement of perforations in thetape being sensed. Thus, if the arrangement of perforations identifiedas 9 is sensed, then there are some mechanical displacementscorresponding to the object part of the arrangement identified as 9 andsome other mechanical displacements corresponding to the specter part ofthe said arrangement-and these two species of displacements areinterrelated as object and specter. A similar arrangement must exist foreach and every possible combination of objects and specters. It isreasonable to infer that the sensing mechanism can consist of a positivelinkage when an object or its specter always appears on the tape. Thisinference is correct, as may be seen by reference to the cited KalkuleXapplica- Vtions and as will be clearly seen in the detailed descriptionwhich follows.

The operation of the sensing mechanism and its isomorphic relation tothe perforations in the tape can be most readily understood from theschematic diagrams of Figures 17, 18, and 19. In Fig. 17, there is showna schematic arrangement for sensing a single set of perforations. (SeeFigures 5, 6, and 7 for an identification of a set of perforations.) Thesensing mechanism for each'set of perforations consists of twointerconnected sensing pins, or needles, 70; the one pin, 70, isarranged to sense the presence of an object (say) and the other pin, 70,is arranged to sense kthe specter of the object. The two pins 70 arepositively connected together by a rocker 72 mounted on a shaft 71. Theshaft 71 may be reciprocated by'a suitable link (or pair of links, asiniFig. 9) by rotating the main shaft 10 (or 11 as the case may be).V Itwill be recalled that the main shaft 10, ,or 11, as the case may be, hasrigidly attached thereto` an eccentric 17 for reciprocating the sensingcarriage through the link 29. This mechanism has been highlyconventionalized in Figures 17, 18, and 19 for more clearlyillustratingthe mode of a sensing operation.v The practical mechanismcorresponding to these elements is "gef-nece 20 fully shown in Figures9, 12, and 13. When the shaft 10 (or 11) turns through a halfrevolution, the shaft 71 is lowered, and the rocker 72 iscorrespondingly lowered-one of the pins 70 nds a perforatiombut theother does not, so that the rocker 72 is turned through an anglecorresponding to the described arrangement of the perforations. From theforegoing description, it is seen that the sensing mechanism is ofextreme simplicity and that it is composed of ,positive mechanicallinkages. This is an extreme contrast to the complications of the priorart record sensing devices. Typical examples of prior art record sensingmechanisms are shown in the patents Goldberg 1,694,009, Pierce1,219,765, and Lascar 2,044,119.

The mechanical isomorphism with the arrangement of perforations in thetape is strikingly evident. If Fig. 18 represents the mechanicalposition of rocker 72 corresponding to an object (or specter, if one sochooses), then Fig. 19 represents the mechanical position of the rocker72 corresponding to a specter (or object if one so chooses). Theposition of rockers and sensing pins, Figures 1,8 and 19 are mutuallyrelated as object and image ,when viewed in a mirror perpendicular tothe tape which passes through the center of shaft 71. It is not improperto view Fig. 18 as representable by the symbol 1V (or if one elects),then Fig. 19 is representable by the symbol (or l if one so elects).Such a representation can be viewed as a first order matrixrepresentation of the perforation arrangement of a single set. There aretwo and only two possible representations, viz., 1 and Suppose four setsof perforations are regarded as an entity, then the number ofarrangements increases considerably. All of the possible arrangements,with the convention that Fig. 18 represents 1 and Fig. 19 represents areshown in Figure 20. Each square in Fig. 20 is properly interpretable asan orthogonant, and there is an isomorphism between the sixteen matricesof Fig. 20 and the symbols of Table A (see also Figures 6 and 8). It hasjust been shown that there is an isomorphism between Figure 20 and thepossible arrangements of four rockers 72 when sensing four sets ofperforations. This is another proof of the isomorphism set out in TableB.

It is now clear that `for any admissible arrangement of performations inthe tape, there is a corresponding arrangement of angular positions ofthe elements 72, and this correspondence is most accurately land terselyde- 'scribed by the well understood and common single technical termisomorphismf The details of the actual mechanism in use for effecting,the establishment ofV a .mechanical isomorphism with -admissible tapeperforations is shown in Figures 9, 10, 12, and 13.

Each sensing pin '70 takes substantially the form of a Greek cross 75,of sheet metal, having a wide opening for clearance about the supportingshaft 71. The upright portion of the said Greek cross can -slidevertically in grooves 77 (Fig. 2l) in the carriage casting 30 and thusassure a limited amount of relative vertical motion for each ofsaid'Greek'crosses 75. One of the horizontal arms of each Greek cross'75 is provided with a notch 73 near the extreme end. The extreme end ofeach Greek cross horizontal arm is provided with vertical ngers 74;

and these fingers are `arrangedto slide in grooves in the casting 30also. The rocker 72 also has the form of a slender Greek cross-itshorizontal arms terminate in off-set trunnionV disks 7?,Y and Yeachdisk78 fits into the above mentioned notch 73 of a pair of sensing fingers70, thus providing the above described positive connection between thesensing pins. The kinematical arrangement just described ismechanicallyidentical with thediagrammatic arrangements shown in Figures 17, 18, and19. Each rocker `72 is provided with a-suitable hub through which passes,the shaft 71 which in turn is supported at its ends by the carriagecasting 30. The downwardly

